1. Field of the Invention
The present invention is directed to a control device for controlling timing of transferring multicolor image data and an image forming apparatus having the control device. Examples of the image forming apparatus are fax machines, color printers, color copiers, and multifunction peripherals providing multiple functions of such machines.
2. Description of the Related Art
Conventionally, there are image forming apparatuses that produce a high quality image with no image shift by using a lesser number of horizontal sync reference signal lines than the number of types of image data handled (for example, see Patent Document 1).
There are also image forming apparatuses in which image data of respective colors of yellow, magenta, cyan and black are sequentially supplied to an image formation control unit at such a timing that, in order to form a single multicolor image, images of the respective colors are superposed one on top of the other by plural image forming units based on a vertical sync signal input from a single vertical sync signal line (e.g. Patent Document 2).    Patent Document 1: Japanese Laid-open Patent Application Publication No. 2000-301766    Patent Document 2: Japanese Laid-open Patent Application Publication No. 2000-218861
However, the above-described conventional image forming apparatuses leave the problem that the timing of transferring image data is affected by noise due to not being able to readily determine an effective area of the image data of each color.